Background It is usually believed that Antinuclear Antibodies are no more prevalent in psoriatic patients than in the general population.

Objectives To assess the prevalence of ANA positivity in a group of psoriatic arthritis patients. To search for possible differences between those who are ANA positive and those who aren’t.

Methods We prospectively analysed according to a designed protocol 47 consecutive patients observed between 00/01/19 and 00/11/14. We recorded the history and physical examination with standard procedures. In all patients the presence of ANA and serum markers of viral hepatitis B and C were determined.

Results We found 38,3% of ANA positivity (Group 1 = ANA positive patients; Group 2 = ANA negative patients). The majority of group 1 patients presented a speckled pattern in title equal or superior to 1/320.

The two groups were similar in respect to gender distribution, age, duration of psoriasis, duration of arthritis, history of concomitant exacerbation of cutaneous and articular disease, history of previous or actual medication with sulphasalazine, extent of cutaneous involvement, presence of nail and scalp psoriasis and prevalence of viral hepatitis B and C.

A greater frequency of sacroiliitis (50% vs 27,6%), of family history of psoriasis (61,1% vs 48,3%) and family history of psoriatic arthritis (22,2% vs 6,9%) was seen in group 1 but didn’t reach statistical significance.

Conclusion Our group of psoriatic arthritis patients shows a high prevalence of ANA positivity.

Although the frequency of patients with sacroiliitis, family history of psoriasis and psoriatic arthritis is greater in the ANA positive group we were not able to show differences with statistical significance.